1. Field of the Invention
The present invention relates to electromagnetic flowmeters and, more particularly, to cathodic protection of measuring electrodes in electromagnetic flowmeters.
2. Description of the Related Art Electromagnetic flowmeters, such as magnetic inductive flowmeters, utilize the principle of electrodynamic induction for flow rate measurement of a fluid medium. In an electromagnetic flowmeter, a magnetic field is generated across a measuring section of a flowmeter pipe through which the medium flows which, by operation of Faraday's law, generates a voltage perpendicular to the flow of the medium and the magnetic field, The induced voltage is measured by a pair of electrodes positioned on opposite sides of the measuring section. This induced voltage that is measured by these electrodes is proportional to the flow velocity of the medium to be measured, averaged over the cross section of the flow meter pipe.
In general, the measuring electrodes used in electromagnetic flowmeters may be made from a range of different materials depending on the intended application of the flowmeter. The suitability of the material of the measuring electrodes for a given media is often not a trivial task, because corrosion effects have to be taken into account. Sometimes a very exotic (i.e., expensive) material such as platinum has to be used to withstand the corrosion effects of a specific media. Furthermore, in cases of corrosion the noise level on the flow measurement is increased.